Nozzle for spraying liquid polymer preparations and spraying method utilising the nozzle

ABSTRACT

A method for spraying a mixture comprising at least a first liquid in the form of a liquid preparation of water-soluble or water-swellable polymers and at least a second liquid, characterized in that it implements a nozzle for simultaneously spraying at least two liquids, comprising: a body provided with a first chamber within which a first liquid flows and a second chamber within which a second liquid flows, each of the two chambers having a through-hole on the outside of the body, a deflector secured to the body arranged downstream from at least one of the through-holes, in the direction of flow of the first and second liquids, said deflector being capable of modifying the direction of flow of the first and second liquids. The invention also relates to a nozzle for implementing the method.

The invention relates to a nozzle for spraying at least two liquids andmore particularly liquid preparations of water-soluble orwater-swellable polymers.

Water-soluble or water-swellable polymers, in particular includingpolyacrylamides are used for multiple agricultural applications such asto limit hydraulic and wind-based soil erosion, to control the slakingof soil in order to thus promote the germination and emergence of crops,without being limited to these interests alone.

The implementation of these polymers is currently performed essentiallyby means of irrigation water. A person skilled in the art can in factrefer as an example to the document titled “Conservation PracticesStandard, Anionic Polyacrylamide (PAM) Application, (Ac.), Code 450”issued by the “Natural Resources Conservation Service” an agency of theUSDA. Polyacrylamides can be added in powder or block form (documentWO96002126) in order to surface irrigation water or in liquidpreparation form within a pressurized system (document WO9857531).

Granted, some methods for spreading or spraying water-soluble orwater-swellable polymers in solid form make it possible to eliminate theuse of irrigation water as the application vector but they arerestrictive. In effect, the spreading of polyacrylamides in powder formon agricultural soils involves specific formulations (document U.S. Pat.No. 7,503,143) or specific materials (document US2016120130) in order toobtain a homogeneous distribution of the polymer on the ground.

Liquid spraying methods therefore remain preferred but several technicalor economic difficulties remain to be overcome.

Spraying of Diluted Polyacrylamide Solutions

The colloidal nature of polyacrylamides with a high molecular weight(>10 million Da) in aqueous solution requires substantial dilution forspraying using standard agricultural nozzles. For example, according toKincaid, D. C and Lentz, R. D. and Lehrsch, G. A (1996) Spray patternsfrom fan-type nozzles for applying PAM to soil surfaces. pp. 457-466.In: Proc. Of Conf. 27. Erosion control technology . . . bringing ithome. USA-WA-Seattle, 1996 Feb. 27-Mar. 1. Int. Erosion Control Assoc.,Steamboat Springs, Colo., the concentration thereof in aqueous solutionmust not exceed 900 ppm (0.9% by weight) for spraying using a commonagricultural sprayer. Furthermore, the spraying pressure must besignificantly increased in order to avoid coalescence of the jet. Thenecessary means to spray these aqueous polymer solutions (verysubstantial quantity of water) are therefore limiting. As an example,the application of 10 kg of polyacrylamide on a surface of 10,000 squaremeters (1 ha) at a concentration of aqueous solution of 1200 ppm causesthe use of 8333 liters of water. Such a quantity of water per surfaceunit is equivalent to an irrigation (FR3009307) which is contrary to thedesire to eliminate irrigation water as vector for the application ofthese polymers.

In this same document (Kincaid & al, 1996), the application ofpolyacrylamide at the concentration of 3000 ppm requires lowering thespray nozzles to 38 mm from the ground and doubling the number ofnozzles due to problems with jet coalescence. In so doing, two spraynozzles make it possible to spray the polyacrylamide suspension onlyover a width of 20 to 30 mm. Such a method cannot be industrialized,since it involves applying a sufficient quantity of these polymers to anagricultural surface within a reasonable length of time.

Spraying Concentrated Polyacrylamide Solutions Using an Atomizer.

Document FR1357705 proposes to use specific equipment, in the case ofhand rotary atomizers, to generate fine drops of uniform size from aconcentrated liquid preparation of water-soluble or water-swellablepolymers. This method which has demonstrated the effectiveness thereofdoes not need to dilute the polymer solution to be sprayed in largequantities of water. However, this method requires specific equipment,the cost or upkeep whereof can be a hindrance.

Spraying with Air Injection Nozzles

The person skilled in the art could spray concentrated liquidpreparations of polyacrylamide as described in document FR1357705 usingair injection nozzles (example nozzle: document U.S. Pat. No.4,828,182). But the small quantity of water contained within theseliquid preparations would limit the efficacy of the polyacrylamides.Indeed, according to Gabriels and De Boodt Theoretical and practicalapproach for determining the optimal moisture content at the moment ofsoil conditioning. Mitt. Deutsch Bodenkund Gesel. 15, 185-203, moistureinfluences the efficacy of soil conditioners applied on agriculturalsoils. Furthermore, the quantity of compressed air and the pressurenecessary to spray thick products through this type of equipmentrequires significant energy consumption that it is difficult to supplyusing an agricultural tractive unit or a self-propelled sprayer. Lastly,since a concentrated liquid preparation of polyacrylamide has a highcontent level of non-volatile solid materials, the compressed air flowwould result in drying out the product during spraying, thus leading tothe application of a pulverulent powder which moreover, by the adherencethereof, would stick to the walls of the nozzle ultimately clogging thenarrow orifices thereof.

None of the aforementioned methods allows an easy application of aconcentrated aqueous preparation of water-soluble or water-swellingpolymers much less in mixture with other hard-to-mix (or evenimmiscible) substances and/or substances incompatible with the aqueoussolution concentrated in polymer.

Even though the fact that adding polyacrylamides to irrigation watermakes it possible to limit the leaching of certain herbicides (seeOliver & al Minimising off-site movement of contaminants in furrowirrigation using polyacrylamide (PAM) I; Pesticides, Australian Journalof soil Research 2006, 44, 551-560) is known, little information existson the benefits of such a combination during the concomitantapplications of polyacrylamide and the herbicide. Indeed, the twoproducts are difficult to mix due to the viscosity but also thepotential instability of the mixture.

The application of polyacrylamides in mixture with a cross-linking agentmakes it possible to produce an in situ cross-linking reaction(documents U.S. Pat. Nos. 3,759,857, 3,875,697, 3,759,197).

This method is interesting, for example, to combat wind erosion.However, the mixture of polyacrylamides and cross-linking agentsconstitutes a reaction medium whose viscosity increases with thecross-linking process until obtaining a final cross-linked product whichtherefore has little or no solubility. Such a mixture is thus difficultto spray. Producing the mixture at the spray nozzle is an attractivesolution. However, the cross-linking phenomenon using sodiumhypochlorite for example is a fast reaction and caking of the reactionmedium may occur in a static mixer positioned just downstream from thespray nozzle causing the obstruction thereof.

Document US 2006/064844 A1 describes a machine making it possible toclean the soils including a system making it possible to mix the soap onthe one hand and water on the other hand. The system is provided withtwo chambers each having a through-hole whereof the axes are secant,combined with a deflector positioned downstream from one of the 2through-holes.

In a field also different from that of spraying polymers, document U.S.Pat. No. 4,361,285 A describes a nozzle for atomizing immisciblematerials having two chambers wherein 2 liquids flow, which mixdownstream from the outlet orifice of each of the chambers. The nozzlefurther comprises a third fluid made up of gas that is inserted betweenthe deflector and the mixture of the 2 liquids.

In a field also different from that of spraying polymers, document U.S.Pat. No. 4,735,359 A describes the combination of two nozzles positionedface to face, each of them being capable of spraying a single liquid.The two liquids mix after the trajectory has been modified beforehand bya deflector.

Therefore, in order to meet the requirement to spray solutions ofwater-soluble or water-swellable polymers, wherein the content by weightof polymer is advantageously between 0.01% and 75%, the Applicant hasdeveloped a nozzle, which additionally offers the possibility of mixingthem during spraying with substances that are nevertheless incompatible.The simplicity of this nozzle makes it inexpensive and the use thereofcauses low energy consumption.

The invention thus relates to a method for spraying a mixture comprisingat least a first liquid in the form of a liquid preparation ofwater-soluble or water-swellable polymers wherein the content by weightof polymer is advantageously between 0.01% and 75% and at least a secondliquid using a nozzle, the features whereof appear hereinafter.

The invention also relates to a nozzle as such for simultaneouslyspraying at least two liquids for the implementation of said method, thenozzle including:

-   -   a body provided with a first chamber within which a first liquid        flows and a second chamber within which a second liquid flows,        each of the two chambers having a through-hole on the outside of        the body,    -   a deflector secured to the body arranged downstream from at        least one of the through-holes, in the direction of flow of the        first and second liquids, said deflector being capable of        modifying the direction of flow of the first and second liquids,        the holes being in practice positioned in relation to one        another so as to allow the mixture of the first and second        liquids at the latest after they have come into contact with the        deflector, advantageously at the latest when they come into        contact with the deflector.

According to a first feature, the axes of the through-holes of the twochambers making up the body are secant such that the first and secondliquids mix before they come into contact with the deflector.

More preferably the axis of one of the holes is positioned in thelongitudinal direction of the body.

In this specific embodiment, the deflector of the nozzle is positioneddownstream from the hole whereof the axis is positioned in thelongitudinal direction of the body.

According to another embodiment, the through-holes of the two chambersmaking up the body are positioned concentrically in relation to oneanother such that the first and second liquids mix at the latest afterthey come into contact with the deflector, advantageously at the latestwhen they come into contact with the deflector

In this embodiment, the deflector of the nozzle advantageously assumesthe form of a cone of revolution, the apex of which is oriented towardthe through-holes and the axis whereof is combined with the axis of saidholes.

For this embodiment, the distance between the apex of the cone and thecenter of the through-holes is advantageously less than 20 mm, moreadvantageously less than 10 mm and still more advantageously less than 4mm.

As already stated, another aspect of the invention relates to a methodfor spraying a mixture, comprising at least a first liquid in the formof a liquid preparation of water-soluble or water-swellable polymerswherein the content by weight of polymer is between 0.01% and 75% and atleast a second liquid, implementing the nozzle previously described.More preferably, the content by weight of polymer for the first liquidis between 5 and 60% and still more preferably between 10 and 50%.

Lastly, the invention also relates to the use of the nozzle previouslydescribed in order to spray at least one preparation of water-soluble orwater-swellable polymers in the fields of agriculture, more particularlyin order to limit soil erosion, rainwater and wastewater treatment,paper making methods and mining extraction.

In other words, the invention also relates to a method for spraying amixture, comprising at least a first liquid in the form of a liquidpreparation of water-soluble or water-swellable polymers and at least asecond liquid, implementing the nozzle previously described, in thefields of agriculture, rainwater and wastewater treatment, paper makingmethods and mining extraction.

The invention and resulting benefits will become clear from thefollowing examples, supported by the attached figures.

FIG. 1 describes a preferred embodiment of the nozzle according to theinvention for which the body of the nozzle 1 comprises two chambers 2and 3 opening onto holes 4 and 5, the axes whereof are secant with thedeflector 6. The axis of the hole 4 is positioned in the longitudinaldirection of the body 1 and the liquids that leave the holes 4 and 5 mixbefore they come into contact with the deflector 6, which is locateddownstream from the holes in the direction of flow.

FIG. 2 describes the nozzle according to the invention in a secondpreferred embodiment wherein the body of the nozzle 1 comprises twochambers 2 and 3, the through-holes 4 and 5 whereof are positionedconcentrically in relation to one another. The deflector 6 is in theform of a cone of revolution, the apex whereof is oriented toward thethrough-holes 4 and 5 and the axis whereof is combined with the axis ofsaid holes, such that the first and second liquids mix at the latestwhen they come into contact with the deflector.

The invention also relates to a method for spraying a mixture comprisingat least a first liquid in the form of a liquid preparation ofwater-soluble or water-swellable polymers wherein the content by weightof polymer is preferably between 0.01% and 75% and at least a secondliquid implementing the nozzle previously described. More preferably,the content by weight of polymer for the first liquid is between 5 and60% and still more preferably between 10 and 50%.

By definition, a water-soluble polymer is a polymer that gives anaqueous solution without insoluble particles when it is dissolved withstirring at 25° C. and with a concentration of 50 g.L⁻¹ in water.

A water-swellable polymer is a polymer that swells and thickens theaqueous solution when it is placed in water at 25° C.

For the method according to the invention, the second liquid is aqueousor organic or a mixture of the two.

Still more preferably, the second liquid assumes the form of awater-in-oil emulsion or the form of an aqueous dispersion of particles.

According to one preferred embodiment, for the spraying method of theinvention the second liquid contains at least one substance of agronomicinterest or at least one substance making it possible to improve thedevelopment or growth of plant material, preferably a substance chosenfrom fertilizers, hormones, microorganisms, mycorrhizae, growthstimulators, growth regulators, phytosanitary products, for examplefungicides, insecticides, plant protectors.

According to another preferred embodiment, for the spraying methodaccording to the invention, at least a second liquid contains at leastone cross-linking agent.

Still more preferably, the cross-linking agent is chosen from the groupcomprising alkali or alkaline earth metal hypochlorites or hypobromites,dialdehydes of formula O═CH—(R)_(n)—CH═O for which R is a saturatedalkylene chain with 1 to 8 carbons and n=0 or 1.

Preferably, for the spraying method of the invention, the first liquidcontaining a water-soluble or water-swelling polymer, assumes the formof a homogeneous aqueous solution or a water-in-oil emulsion or adispersion of polymer particles in aqueous phase.

For the water-in-oil emulsion, the water-soluble or water-swellablepolymer is in droplets of water in suspension in the mobile phase thatis the oil.

The dispersion of polymer particles in aqueous solution containsparticles of at least one water-swellable or water-soluble polymer insuspension in an aqueous solution containing at least one compoundchosen from a mineral salt, an organic salt, a dispersant organicpolymer and mixtures thereof.

Preferably, for the spraying method of the invention at least onewater-soluble or water-swellable polymer contained within at least afirst liquid to be sprayed according to the method of the invention, isan acrylamide copolymer.

Advantageously, the comonomers of the acrylamide are non-ionic and/oranionic monomers.

The nonionic monomer or monomers can be chosen, in particular, from thegroup comprising water-soluble vinyl monomers. Preferred monomersbelonging to this class are, for example methacrylamide,N-isopropylacrylamide, N,N-dimethylacrylamide and N-methylolacrylamide.It is also possible to use N-vinylformamide, N-vinyl acetamide,N-vinylpyridine and N-vinylpyrrolidone, acryloyl morpholine (ACMO) anddiacetone acrylamide.

The anionic monomer or monomers can be chosen chosen from acrylic acid,methacrylic acid, itaconic acid, maleic acid,2-acrylamido-2-methylpropane sulfonic acid (ATBS), vinylsulfonic acid,vinylphosphonic acid, said anionic monomer being non-salified, partiallysalified or totally salified.

The last aspect of the invention relates to the use of the nozzle of theinvention to spray at least one preparation of water-soluble orwater-swellable polymers in the fields of agriculture, more particularlyin order to limit soil erosion, rainwater and wastewater treatment,paper making methods and mining extraction.

In the field of agriculture and more specifically for soil erosion, thewater-soluble or water-swellable polymer is advantageously sprayedconcomitantly with at least a second liquid containing at least onesubstance of agronomic interest or at least one substance making itpossible to improve the development or growth of a plant material.

The advantages of the nozzle of the invention, the spraying method usingthis nozzle and the use thereof have been illustrated in light of thefollowing examples, but are not limited thereto.

EXAMPLE 1 Spraying of a Concentrated Mixture of Polyacrylamide with aHigh Molecular Weight

According to the method of the invention concentrated mixtures ofpolyacrylamide with a high molecular weight were sprayed using abi-liquid mirror nozzle equipped with two separate outlet holes.

This nozzle (corresponding to FIG. 1) was modeled in three dimensionsthen printed using an additive method from PET using an “Ultimaker 2+”printer.

The total length of the nozzle is 67 mm, the diameter of thecross-section including the deflector is 12 mm, the diameter of theholes of the chambers is 2 mm and lastly the surface area of thedeflector is 112 mm².

The nozzle was next equipped with the necessary gaskets before beingintroduced into a nozzle holder of the “Airjet Bi-Fluid” model of theTeejet brand. This nozzle holder is normally used for spraying with airinjection. The use thereof has been adapted in order to allow for theconveyance of two liquids toward the nozzle previously drawn andprinted.

Water was circulated in chamber 3 of the nozzle and various concentratedliquid preparations of polyacrylamides in chamber 2.

The polyacrylamides are copolymers of acrylamide and sodium acrylate(70/30, mol %) with a molecular weight of between 10 and 20 millionDaltons.

The concentrated liquid preparations (25% by weight) used are describedin the following table:

Preparation Formulation A Aqueous dispersion B Water in oil emulsion

The flow rate of each liquid and the polymer concentrations of themixtures thus sprayed are indicated in the following table:

Water Polymer concentration Flow rate Flow rate of the sprayed mixtureTrial Preparation (L/min) (L/min). (% by weight) 1 A 0.3 2.2 3 2 B 0.42.2 3.85

We obtain spraying in a homogeneous web over a width of more than 40 cm.

According to Kincaid & al (1996) the polymers used cannot be sprayedcorrectly at a concentration exceeding 900 ppm by weight (0.9% byweight). With the method of the invention, it was possible to spray thesame polymers at a concentration more than times higher.

EXAMPLE 2 In Situ Cross-Linking of Polyacrylamide

A method for in situ cross-linking of polyacrylamide was implemented inorder to stabilize a soil as described in the document “Crosslinking ofacrylamide polymers” U.S. Pat. No. 3,759,857 but implementing the nozzleand the spraying method of the invention.

A liquid preparation of polyacrylamide (molecular weight around 100,000Da) and a solution of sodium hypochlorite (cross-linking agent) werecirculated in each of chambers 2 and 3 of the spray nozzle (identical tothat of example 1).

The aim was for the two liquids to mix upon contact with the surface ofthe deflector (also called mirror) of the nozzle.

The table below summarizes the spraying parameters used:

Concentration of the active ingredient Chamber of Liquid (% by Flow ratewithin the sprayed the nozzle weight in water) (mL/min) mixture g/L) 2Polyacrylamide 11.5% 400 24.9 3 Sodium hypochlorite 1450 0.8 0.1%

Several nozzles were arranged on a spray bar in order to easily applythe mixture of the polymer and the cross-linking agent on the surface oftubs filled with a sandy soil. Once the mixture was applied, thecross-linking induces the formation of a stabilizing layer on thesurface of the soil.

It should be noted that the spray nozzles are easily cleaned afterspraying. No cross-linking and therefore no clogging occurred inside thespraying equipment.

1. A method for spraying a mixture comprising at least a first liquid in the form of a liquid preparation of water-soluble or water-swellable polymers and at least a second liquid, wherein said method comprises implementing a nozzle for simultaneously spraying at least two liquids, the nozzle including: a body provided with a first chamber within which a first liquid flows and a second chamber within which a second liquid flows, each of the two chambers having a through-hole on the outside of the body, and a deflector secured to the body arranged downstream from at least one of the through-holes, in the direction of flow of the first and second liquids, said deflector being capable of modifying the direction of flow of the first and second liquids.
 2. The method for spraying according to claim 1, wherein the holes are positioned in relation to one another so as to allow the mixing of the first and second liquids at the latest when the liquids come into contact with the deflector.
 3. The method for spraying according to claim 1, wherein the axes of the holes are secant such that the first and second liquids mix before they come into contact with the deflector.
 4. The method for spraying according to claim 1, wherein the axis of one of the holes is positioned in the longitudinal direction of the body.
 5. The method for spraying according to claim 4, wherein the deflector is positioned downstream from the hole having the axis that is positioned in the longitudinal direction of the body.
 6. The method for spraying according to claim 2, wherein the through-holes are positioned concentrically in relation to one another such that the first and second liquids mix at the latest when they come into contact with the deflector.
 7. The method for spraying according to claim 6, wherein the deflector assumes the form of a cone of revolution wherein the apex thereof is oriented towards the through-holes and wherein the axis of the deflector is combined with the axis of said holes.
 8. The method for spraying according to claim 1, wherein the second liquid is aqueous or organic or a mixture of the two.
 9. The method for spraying according to claim 1, wherein the second liquid assumes the form of a water in oil emulsion or the form of an aqueous dispersion of particles.
 10. The method for spraying according to claim 1, wherein the second liquid contains at least one substance of agronomic interest or at least one substance making it possible to improve the development or the growth of plant material.
 11. The method for spraying according to claim 1, wherein the second liquid contains at least one cross-linking agent.
 12. The method for spraying according to claim 1, wherein the first liquid comprises an acrylamide copolymer.
 13. The method for spraying according to claim 1, wherein the weight content of polymer in the first liquid is between 0.01% and 75%.
 14. The method for spraying according to claim 1, wherein the method is implemented in the fields of agriculture.
 15. A nozzle for simultaneously spraying at least two liquids, the nozzle including: a body provided with a first chamber within which a first liquid flows and a second chamber within which a second liquid flows, each of the two chambers having a through-hole on the outside of the body, and a deflector secured to the body arranged downstream from at least one of the through-holes, in the direction of flow of the first and second liquids, said deflector being capable of modifying the direction of flow of the first and second liquids, wherein the through-holes are positioned concentrically in relation to one another such that the first and second liquids mix at the latest when they come into contact with the deflector.
 16. The nozzle according to claim 15, wherein the deflector assumes the form of a cone of revolution the apex whereof is oriented toward the through-holes and the axis whereof is combined with the axis of said holes.
 17. The method for spraying according to claim 13, wherein the weight content of polymer in the first liquid is between 5 and 60%.
 18. The method for spraying according to claim 13, wherein the weight content of polymer in the first liquid is between 10 and 50%.
 19. The method for spraying according to claim 1, wherein the method is performed in order to limit soil erosion, treat rainwater or wastewater, as part of a paper making process, or during mining extraction.
 20. The method for spraying according to claim 2, wherein: the axes of the holes are secant such that the first and second liquids mix before they come into contact with the deflector; and/or the axis of one of the holes is positioned in the longitudinal direction of the body, and the deflector is positioned downstream from the hole having the axis that is positioned in the longitudinal direction of the body. 